1. Field of the Invention
The present invention relates generally to laser sighting devices and telescopic sighting devices, such as laser aiming devices and shooting scopes respectively, useable with a projectile firing device or firearm.
2. Description of Related Art
The art to which the invention relates includes firearm scopes such as riflescopes, handgun scopes and archery scopes, hereinafter "shooting scopes", used to provide the shooter with an enlarged or otherwise enhanced image or field of view of a distant target.
Virtually all shooting scopes, except for most archery scopes, are "refracting" telescopes. Refracting telescopes typically have two parts: the "objective," which is usually a lens, and the "eyepiece," which can be a single lens or group of lenses.
The objective and eyepiece are typically mounted within the confines of a substantially cylindrical tube referred to as a "scope tube." When the user looks through the eyepiece of the shooting scope he typically sees intersecting reticles or crosshairs, sighting posts, sighting rings, targeting spots, or the like, hereinafter referred to as "aiming indicia" superimposed on the distant object in the field of view of the scope. The aiming indicia is designed to provide the user with a point of reference indicating the intended the area of the target the projectile is to strike after it is fired from the weapon. The shooting scope may also include various adjustment knobs, associated with the scope tube, to provide the user with a means of adjusting the aiming indicia and thus his point of aim prior to firing the weapon to which it is attached. The means of fine adjustment is designed to allow the user to account for certain variables such as windage and projectile rise or drop.
There are primarily two types of riflescopes: (1) fixed power, and (2) variable power scopes. A fixed power scope has a constant magnification factor, and is substantially focused at any viewing range. Variable power scopes are believed to be more versatile as the magnification factor can be adjusted and while most also have a focus free construction, some may be focused to adjust for parallax. The field of view of fixed power scopes remains constant at a given distance; whereas, the field of view through a variable power scope at a fixed distance will change (i. e., decrease) when the magnification factor is increased.
The art to which the invention relates also includes laser pointing or laser aiming devices, but more particularly to devices for generating and projecting a laser beam at a distant target as opposed to optically superimposing a dot of constant size on a distant target, hereinafter "laser targeting means" or "laser targeting devices." For example, the laser targeting devices manufactured or sold by the following entities are believed to partially comprise the art to which the invention relates: Action Arms Ltd. of Philadelphia, Penn., ADCO International of Woburn., Massachusetts, AFKO Technologies Inc. of Irvine, Calif., Aimpoint EISA of Herndon, Va., Alpec Team of Danville, Calif., Applied Laser Systems of Grants Pass, Oregon, Aro-Tek Ltd. of Pacific, Wash., B-Square of Fort Worth, Tex., Bushnell/Bausch & Lomb Sports Optics of Overland Park, Kans., Gilmore Sports Concepts Inc. of Tulsa, Okla., Laser Devices of Monterey, Calif., Simmons Outdoor Corp. of Thomasville, Ga., TacStar Industries of Cottonwood, Ariz., and Tasco of Miami, Fla.
The laser beam generated by a laser targeting device is preferably collimated and is therefore capable of projecting a fine tightly confined beam of laser light, and thus a dot of laser light corresponding to the circumference of the beam, on the intended distant target. Of course, variations in the collimation may produce shapes other than dots, but dots are believed to be the most common and easy to produce.
Like most dots created by laser beams, the size of the dot of laser light projected by the laser targeting devices "grows" as the distance between the laser targeting devices and the target upon which the dot is projected increases. If the size of the laser dot and distance the laser targeting device is located from the target is plotted on a graph, the resulting growth rate would be substantially linear.
If the rate at which the spot of laser light grows is known, which is typically dependent upon the specific laser targeting device used, and the shooting scope can measure the size of the relative approximate spot size as it appears on a distant target, the relative distance the laser light source is from the target can be determined by extrapolation between known data points or reference to the graph.
For example, if the dot were one inch in diameter at one-hundred yards and two inches in diameter at two-hundred yards. Similarly, one could expect the diameter of the dot to be three inches at three-hundred yards, three and one-half inches at three-hundred fifty yards, and four inches at four-hundred yards. Similarly the dot would be larger at longer ranges, for example, ten inches at one-thousand yards.
Until now, a shooting scope and laser targeting system, designed to determine target distances by determining an approximate size of a laser dot projected on the distant target, has not been invented.